Crossed Beams and Theoretical Study of the (NaRb)⁺ Collisional System

Abstract

Ion-atom collisions are one of the most assiduously studied topics in Chemical Dynamics, since their relative simplicity make their study easy to set up and carry out. When both colliding species are alkali atoms this interest becomes still greater, not only because their dynamics can be studied using simple models such as those involving pseudopotentials, but also because species in excited electronic states are readily formed by the collisions (either by direct excitation or via electron exchange processes) whose fluorescent decay emissions can furnish useful information and offer the perspective of such interesting technical applications as lasers and gas-discharge lamps. While beam-chamber experiments were very easy to perform on these systems, it was the development of the crossed beams technique that finally permitted their study in carefully selected conditions to obtain true cross-section data. Foremost in this field were Aquilanti el al whose work included the determination of collision cross-sections for a number of symmetrical and unsymmetrical collision systems, being able in some cases to resolve the fluorescent emissions into their J-components, and even to study polarisation fractions accurately enough to determine the branching ratios between MJ states (for a full review of papers in this field see [1] and references mentioned there).